Just the posts from the scammer himself which you omitted from your quote. Sure, you could claim, "well, he's a scammer so maybe he was lying", but he had previously been silent for some months following his 'LetItRide' scam being exposed, albeit he had managed to con several hundred btc out of people through it, and he had absolutely no reason to come out of hiding in order to make the demand that he did.

There would have been nothing to gain from him making this up and, given that he did not in the end have to "bring a shit storm" over the matter, I'm betting he was indeed given back those 375 BTC.

I said as much at the time but this thread was so full of fawning fanbois with dollar-signs in their eyes at how this ICO was going to make them rich while they slept because there was so many bitcoins being invested in it, nobody was interested.